Water insoluble



v e 25;, 1958 '1'. c. NOHEJL 2,824,526

Anx-xERENcE TREATMENT OF METAL SURFACES WA INSOLUBLE ME CARBON/l TE I nvwzzvrom THOMAS C. NO HEJL United States Patent ADHERENCE TREATMENT OF METAL SURFACES Thomas C. Nohejl, Downers Grove, Ill., assignor to National Aluminate Corporation, Chicago, 11]., a corporation of Delaware Application December 19, 1955, Serial No. 553,930 35 Claims. (Cl. 104-1) This invention relates to a new and improved frictional treatment for metal surfaces and more particularly to a method and a composition for increasing the coefiicient of friction between the contacting surface of a metal wheel and a metal surface on which it operates. The invention is especially concerned with the provision of novel chemical means for preventing the wheel slippage between locomotive wheels and rails.

The past several decades have produced railway locomotives possessing great power and weight, thus enabling long, heavily-laden trains who pulled by single engines. With the advent of the extremely heavy locomotive it was felt that driving wheel slip would be eliminated. It

, was soon discovered, however, that the increased static weight carried on the driving wheels did not solve the problem to any great extent. Track sanding techniques Were developed but this only partially alleviated the condition. Wheel slippage has proven to be an erratic condition which has not in all cases been satisfactorily explained.

In one explanation of the problem rail slip is said to result from a tough invisible oil film on the wear band of the rail. Trafiic and heat destroy this film and high coefficient of friction results. When a light rain occurs or when the rails reach the dew point, as the result of the relatively high humidity, a water vapor film forms across the wear band where it may contact oil deposits on the edge of a rail with the result that a film of oil creeps through and replaces the water film. The oil'deposits on the rail sides act as reservoirs for the formation of new oil films and the water acts as the transport ing agent. The oil deposits on the rail come from journal box oil leakage by way of the outside face and outer portion of the tread of the car wheels. There are other sources of contamination such as road crossings, rail lubricators, and the like.

The importance of solving the problem is strikingly illustrated when it is realized that only 15% of the engines weight can be utilized as tractive force when the rails are greasy and moist, and 30% when the rails are clean and dry and sanded. Even a small improvement in these figures, as expressed in the terms of increased coefficient of friction, would enable railway locomotives to operate more efiiciently and economically as well as providing improved braking for railway locomotives and rolling stock.

It istherefore an object of this invention to provide a method for improving the coefiicient of friction between contacting surfaces movingone with respect to the other particularly where at least one of said surfaces is metal.

Another object of this invention is to provide a method for raising the coefiicient of friction between railway car wheels and rails.

A further object is to provide a method of decreasing slippage between railway wheels and rails.

Yet another object is to raise the coefficient of friction between railway car'wheels and rails having an oil film thereon.

' many well known metal carbonates in cold water may be 2,824,526 C6. Patented Feb. 25,

Still a further object of the invention is to provide a rail treating frictional producing composition which'is relatively easy to prepare and to apply.

Still another object of the invention is to provide a new and improved method for .treating the contacting surfaces of railway car wheels and/ or tracks in order to increase the coefficient offriction therebetween. objects will appear hereinafter. p

In accordance with the invention it has been found that the coefficient of friction between contacting surfaces, particularly contacting metal surfaces, or where at least one of said surfaces is metal, can be increased by applying to at least one of said contacting surfaces a coating of 'a water insoluble metal carbonate. In a preferred embodiment the water insoluble metal carbonate is fine particle size calcium carbonate.

As shown in the drawing, the rail 1 has a bearing surface 2 to which the coating 3 of the antislip composition is applied. The coating of the antislip composition may also extend over the surface 4 which comes into contact with the wheel flange of the wheels of locomotives and railway cars.

In its practical application, the invention is particularly important where exceptionally high pressures are developed at the contacting surfaces, as is the case, for ex-. ample, between the steel surfaces of. railway car wheels and the tracks upon which railway vehicles operate. In the preferredpractice of the invention good results have been obtained by applying to at least one of said contacting surfaces a thin film of a composition composed.

essentially of a pasty suspension of at least 2% by weight, preferably 5% to 50% by weight and even more preferably 20% to 35% by weight of a water insoluble meta By the expression water insoluble metal carbonates,

isv meant to include those carbonates and bicarbon'ates which are soluble in cold water to an extent of notmore than 3% by weight. The approximate solubilities of the found in Langes Handbook of Chemistry, 8th edition,

Handbook Publishers, Inc., 1952. Examples of some of.

thecommon water insoluble metal carbonates that may be used are: cupric carbonate, ferrous carbonate,,lead carbonate, barium carbonate, magnesium carbonate, manganese carbonate, mercurous carbonate, mercuric car-. bonate, zinc carbonate, cadmium carbonate, cobaltous carbonate, nickel carbonate and calcium carbonate. In.

addition. to the several carbonates listed, mixtures thereof may be used. Also useful are the mixed naturally oc- Other In another preferred embodiment the water insoluble metal carbonate is com curring carbonates such as dolomite, which is a mixture of calcium and magnesium carbonates.

Of the water insoluble metal carbonates shown as being useful, calcium carbonate is by far the most important. It is the most commonly occurring compound which is available in a wide variety of forms and particle sizes.

In a special embodiment it is desirable to use a very fine particle size calcium carbonate. The individual average particle size of these fine calcium carbonates should not be greater than 1 micron and are preferably 0.1-0.3 micron or less.

For purposes of illustration several water insoluble metal carbonates, including a variety of calcium carbonates, are listed below in Table I. Where appropriate, and also for purposes of comparison, several of the commercially available calcium carbonates are shown with their respective average particle sizes in microns.

. Finely divided nickel carbonate- Whiting, calcium carbonate Reagent grade, calcium carbonate- Lithium carbonate...

Colloidal Dolomite.

A B C D E. F. G H I. J. K.

Another type of fine calcium carbonates that are useful in the invention are the so-called amine-coated calcium carbonate pigments described in U. S. Patent 2,709,160. The starting calcium carbonates have a particle size of 0.1 micron or less and are treated with a 10-18 carbon primary n-alkyl amine (higher amine) or rosin amine whereby the surface of the fine calcium carbonate is coated with from about 0.2% to about 5% of said amine, based on the weight of the calcium carbonate. The disclosure of U. S. Patent 2,709,160 is incorporated herein by reference.

The paste-like water insoluble metal carbonate suspensions which are as indicated, a preferred embodiment of the invention, are not limited to the employment of any particular non-lubricating liquid as the suspending medium. The liquids may be broadly classified as hydrophilic non-lubricating liquids and hydrophobic non-lubricating liquids.

The preferred hydrophilic liquids are water and hydrophilic aliphatic alcohols, including, for example, lower aliphatic monohydric alcohols such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol, or mixtures thereof; water soluble ether alcohols, such as, for example, the methylether of diethylene glycol or the ethylether of diethylene glycol; and hydrophilic polyhydric alcohols such as, for example, ethylene glycol, 1,2-propylene glycol or butylene glycol.

The preferred hydrophobic liquids are petroleum base solvents, preferably containing a large amount of arcmatic components; the low molecular weight chlorinated hydrocarbons such as carbon tetrachloride, ethylene dichloride; the aromatic hydrocarbon solvents of which benzene, xylene and toluene are exemplary; hydrocarbon ethers, e. g., methyl, hexyl and propyl ethers; mineral spirits; pinene; naphtha and kerosene are also several others that could be used. It is obvious any liquid that is non-lubricating and would not interfere with the frictional-improving action of the water insoluble metal carbonates may be used. The preferred non-lubrieating hydrophobic liquids have a viscosity at 26 C. not greater than 35 centipoises and preferably not greater than 8.5 centipoises. Listed below in Table II are several such liquids showing their viscosities at 26 C.

In Table II above, solvents Nos. 1, 2, 6, 7 and 9 are petroleum base solvents containing varying amounts of aromatic components. Solvent No. 10 is an automotive lubricating oil and is ineffective when used in the invention.

The term non-lubricating as used herein with reference to the liquids employed to suspend the water insoluble metal carbonates is intended to cover those liquids which have no substantial lubricating effect. It would be possible, of course, for a liquid to have a slight lubricating effect which is more than counteracted by the antislip properties of the water insoluble metal carbonates.

Evaluation of the invention In order to evaluate the various compositions as agents for improving the coefiicient of friction between railway car wheels and rails, the following test apparatus was employed. A slotted wooden holder comprising two strips of wood was mounted on a bench. The holder was so constructed 'as to contain a piece of steel four inches long, one inch wide and one-quarter inch thick, herein referred to as a rail. The steel rail was heat treated and had a tensile strength of 164,200 pounds per square inch, a yield point of 159,200 pounds per square inch, a percent elongation of 17.3%, and decarburization to a depth of 0.008 inch. An analysis of this steel showed it to contain the following:

Percent by weight Carbon .3 l Manganese .58 Phosphorus .016 Sulfur .016 Silicon .29 Chromium 1.000 Molybdenum a- .222

A U-shapcd member made of heavy strap steel was formed having two perpendicular pieces attached to the tips of the U. A %g" diameter hole was bored in the center of the base of the U. A 1%" diameter steel ball having a Brinell hardness of 500 was welded to a threaded steel rod. The threaded steel rod was placed in the hole formed in the U-shaped steel member and fastened with a nut so that the steel ball was within the cradle of the U; The perpendicular arms were fitted with small steel boxes capable of holding lead shot or other weighted material. The U-shaped member was placed on the rail so the steel ball rested on the surface. On either side of the inverted U, wires were attached at a point slightly above the rail surface. Next to the other ends of the wire was a short piece of string attached over a fixed pulley, the top of which was approximately coplanar with the surface of the rail. At the opposite end of the string was a suspended container which could be filled with weights.

In operation,- the boxes were filled with lead shot in an amount which, whenincluded with the weight of the cradle and fixtures, were calculated to exert a pressquare inch. The weight of the U-shaped member and ball was 3,065 grams, which, for the purposes of the experiment may be considered as the operative downthe wear band of the wheels of the locomotive.

on operating railway locomotives merely by providing a swabbing or similar type applicating mechanism to apply the material either 'to the surfaces of the rail or to It may The water insoluble metal carbonates may be slurried in the non-lubricating liquid in the amounts previously indicated and routine experimentation can determine the exact amounts necessary or desirable for a particular application. While it is desirable for some purposes to produce a paste of uniform consistency, slurries'that must be agitated before use to suspend the water insoluble metal carbonates may be used with good results. When the pastes are used it is preferable to allow them to dry whereby optimum results may be achieved. A

The invention is not limited to any particular method of apparatus for applying the antislip composition to the ward pressure. The suspended container 'was filled gradbe applied either alone or in conjunction with conven ually with lead shot until the steel ball just started to slide. t10na1 sand1ng p qu This amount of weight is considered as the force neces- While the invention is primarily designed to be applied sary to overcome the friction existing betw en the ball to the contacting surfaces of diesel locomotive wheels and the rail. By using these two factors, the coefficient and the rails upon which they run, .it also has equal of friction may readily be evolved from the following 10 effectiveness when it is applied to the wheels of other simple equation; railway car vehicles such as boxcars, passenger cars, and F the like. It also has equal application in the application Coefficient of friction= to the contacting surfaces of the wheels and rails of such forms of transportation as streetcars and cars used where P equals 3,065 grams and F equals the Weight in the operation of various types of mines, necessary to move the 3,065 grams. The invention is also useful in increasing the coefficient At the start of each series of tests the rail was cleaned of friction between such surfaces as nuts and bolts, with scouring powder, rinsed with distilled water and pinion shafts and gears, where such are frictionally dried with cellulose tissues. Periodic inspections were jointed, conveyor belts transporting various metal ob-' made at the contacting surface and when scratches ocjects such as parts, containers and similar articles. An curred, the ball and rail were polished with emery paper important application is the coating of metal containers to renew the surface finish. and drums whereby they may be more readily stacked To simplified the experimental results the forces neceswithout danger of falling or rolling. sary to'overcome the friction of the steel ball and the The invention is hereby claimed as follows: rail were recorded in grams. The tests were run by 1. The method of improving the frictional contact simply smearing a light coating of the composition to between two metal surfaces capable of motion one with be tested over the rail and running the tests while the marespect to the other which comprises applying to at least terial was still wet unless otherwise indicated. one of said surfaces a thin coating of a water insoluble In order to establish a working basis for comparing metal carbonate, and bringing said surfaces into contact the test results obtained, series of tests were run wherewith one another with said carbonate therebetween. in both the rail and the steel ball were perfectly clean. 2. The method of improving the frictional contact The average of ten such tests showed a force of 1,835 between two metal surfaces capable of motion one with grams necessary to move the ball. When a visible film respect to the other which comprises applying to at least of journal box oil was applied to the rail the average one of said surfaces a thin coating of calcium carbonate, was 620 grams. All of the tests hereinafter described and bringing said surfaces into contact with one another. were conducted with a film of journal box oil at all with said carbonate therebetween. times initially apparent on the surface of the rail. Hence, 3. The method of improving the frictional contact readings in excess of 620 indicated compositions of enbetween two metal surfaces capable of motion one with hanced antislip properties. respect to the other which comprises applying to at least The results of the tests using various compositions of 40 one of said surfaces a thin coating of a calcium carbonate the invention are shown in Table III. having an average particle size not greater than 1 micron, 1

TABLE III Percent Average Test N 0. Metal Oarbo- Solvent, Table II and others by wt Physical Force in nate, Table I 01 Metal Form I Grams Carbonate 1 Blank (oiled 620.

. specimen). 2---- 1--- 2,267. 9 2,100. Water 2,100. by vol. each of water- 2,000.

isopropyl alcohol. do 2,075. 2,100. 1,850. 2,132. 2,025. 1.975 (dry). 1,800 (dry). 1,750. 1,800.

Dusted on Specimen... 1,100. 30 I Slurry 1,700.

and bringing said surfaces into contact with one another with said carbonate therebetween.

4. The method of improving the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least one of said surfaces a thincoating of a suspension of a water insoluble metal carbonate in a non-lubricating liquid, and bringing said surfaces into contact with one another with said carbonate therebetween.

5. The method of improving the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least surface to be treated. The compositions canbe applied 7 one of said surfaces a thin coating of a suspension of calcium-carbonate in'anon-lubricating liquid, and bring: lug said surfaces intofcontact with one another with said carbonate therebetween.

6. The method of claimwherein the calcium carbonate has an average particle size of colloidal fineness.

7. The method of claim 5 wherein the calcium carbonate is present in the liquid within the range of 2% to 50% by weight.

8. The method of improving the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least one of said surfaces a thin coating of a water insoluble metal carbonate suspended in a non-lubricating hydrophilic liquid.-

9. The method of improving the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least one of said surfaces athin coating of calcium carbonate suspended in a non-lubricating hydrophilic liquid, and bringing said surfaces into contact with one another with said carbonate therebetween.

10. The method of claim 9 wherein the calcium carbonate has an average particle size of not greater than 1 micron.

11. The method of claim 9 wherein the calcium carbonate is present in the non-lubricating hydrophilic liquid within the range of 20% to 35% by weight.

12. The method of claim 9 wherein the non-lubricating hydrophilic liquid is water.

13. The method of claim 9 wherein the non-lubricating hydrophilic liquid contains a water soluble lower aliphatic alcohol.

14. The method of improving the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least one of said surfaces a thin coating of a water insoluble metal carbonate in a non-lubricating hydrophobic liquid, and bringing said surfaces intocontact with one another with said carbonate therebetween.

15. The method of improvingv the frictional contact between two metal surfaces capable of motion one with respect to the other which comprises applying to at least one of said surfaces a thin coating of a suspension of calcium carbonate in a non-lubricating hydrophobic liquid, said liquid having a viscosity at 26 C. not greater than centipoises, and bringing said surfaces into contact with one another with said carbonate therebetween.

16. The method of claim 15 wherein the calcium carbcnate has an average particle size not greater than 1 micron.

17. The method of improving the coefiicient of friction between railway car wheels and tracks which comprises applying to at least one of the contacting surfaces a thin coating of a water insoluble metal carbonate.

18. The method of improving the coeflicient of friction between railway car wheels and tracks which comprises applying to at least one of the surfaces a thin coating of calcium carbonate.

19. The method of claim 18 wherein the calcium car'- bonate has an average particle size not greater than 1 micron.

20. The method of improving the coeflicient of friction between railway car wheels and tracks which comprises applying to at least one of the'surfaces a thin coating of asuspension of calcium carbonate in a non-lubricating liquid.

2 1. The method of claim 20 wherein the calcium: carbonatc' has an average particle size not greater than 1 micron.

22. The method of claim 20 wherein the calcium carbonate is present in the liquid within the range of 2% to 50% by weight.

23. The method of improving the coefficient of friction between railway car wheels and tracks which comprises applying to at least one of said surfaces a thin coating of a suspension of calcium carbonate in a non-lubricating hydrophilic liquid.

24. The method of claim 23 wherein the calcium carbonate has an average particle size not greater than 1 micron.

25. The method of claim 23 wherein the calcium car bonate is present in the non-lubricating hydrophilic liquid within the range of 20% to 35% by weight.

26. The method of claim 23 wherein the non-lubricatinghydrophilic liquid is water.

27. The method of claim 23 wherein the non-lubricating hydrophilic liquid contains a water soluble lower aliphatic alcohol.

28. The method of improving the coefficient of friction between railway car wheels and tracks which comprises applying to at least one of the contacting surfaces a thin coating of a suspension of calcium carbonate in a nonlubricating hydrophobic liquid. said liquid having a viscosity at 26 C. not greater than 35 centipoises.

29. A railway rail having its wheel bearing surfaces coated with a coating of a water insoluble metal carbonate.

30. A railway rail having its wheel bearing surfaces coated with a coating of calcium carbonate.

3l. A railway rail having its Wheel bearing surfaces coated with a coating of calcium carbonate having a particle size not greater than 1 micron.

32. A structure having two metal surfaces capable of motion one with respect to the other and adapted to engage each other by frictional contact, at least one of said surfaces being coated with a thin coating of a water insoluble metal carbonate.

33. A structure having two metal surfaces capable of motion one with respect to the other and adapted to engage each other by frictional contact, at least one of said surfaces being coated with a thin coating of a water insoluble metal carbonate having an average particle size not greater than one micron.

34. A structure having two metal surfaces capable of motion one with respect to the other and adapted to engage each other by frictional contact, at least one of said surfaces being coated with a thin coating of a colloidal water insoluble metal carbonate.

35. A structure having two metal surfaces capable of motion one with respect to the other and adapted to References Cited in the file of this patent UNITED STATES PATENTS Connolly Apr. 17, 1928 OTHER REFERENCES TextileResearch Journal, vol. XXV, No. 5, May 1955, paper by H. M. Brown et al. delivered Feb. 16-18, 1955.

U S DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,824,526 Thomas (20 Nohejl February 25, 1958 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let oers Patent should read as corrected below.

Column '7, line 14-, claim 8, after the word "liquid" strike out the period and insert instead he and bringing said surfaces into contact With one another with said carbonate therebetween. Q

This certificate supersedes Certificate of Correction issued 4 April 29, 1958.

,Signed and sealed this 24th day of June 1958.

(SEAL) Attest:

KARL Ha AXLINE Attesting Officer ROBERT C. WATSON Conlnissioner of Patents 

17. THE METHOD OF IMPROVING THE COEFFICIENT OF FRICTION BETWEEN RAILWAY CAR WHEELS AND TRACKS WHICH COMPRISES APPLYING TO AT LEAST ONE OF THE CONTACTING SURFACES A THIN COATING OF A WATER INSOLUBLE METAL CARBONATE. 